Isolate

This creates a fresh git worktree branched from the latest origin/main before you start any task work. It handles the tedious stuff: fetching upstream, detecting your parent branch from reflog, setting up the worktree directory, installing dependencies based on whatever lockfiles it finds, and running a baseline test suite to confirm you're not starting from a broken state. If you're already in a worktree, it freshens the branch instead. The parent branch detection is clever but defaults to main when reflog is empty, which covers the edge cases. Pairs with a /ship command that cleans everything up when you're done.